Research On Steering Characteristic Based On Tire Lateral Deflection

Automobile tire's lateral characteristics and the centre of vehicle steering have an important influence on the steering performance of the vehicle.Automobile tire's lateral characteristics not only affect the tire wear and life but also the vehicle handling and stability.The design of the automobile steering mechanism directly affects the two-wheel steering angle relationship,and influence the car's pure rolling steering.Whether the car steering is pure rolling is determined by the steering center,which is closely linked to vehicle rollover and tail flick.Therefore,to solve the above problems,this paper is the basic part of the study;at the same time,what differences between the left and right front wheels when the car at high and low speed are also discussed.The main contents are as follows:(1)To establish the force balance model of the front and rear wheel drive vehicle at low-speed;an answer using analytic method and graphic method are applied respectively.Finding what factors affect the forces in the balance model and obtaining the corresponding curve relationship.The results prove that graphic analytic method is a more direct and simple method.(2)Based on analysing of the front and rear drive vehicle low-speed steering force balance model,taking the tire cornering stiffness proposed by automobile steering into account,then the concept of the ideal line is put forward.Fixing the Ackerman principle after considering tire cornering stiffness,then we can gains the fixed expression and analysis the influence parameters of the expression;The value of the steering ideal line is provide a theoretical reference in the situation when all factors that affect side slip angle need to be taken into consideration,and it is of great importance to the automobile steering angle control and the design of steering device.(3)For the modern automobile steering mechanism,there is only one point or several points that can fit the ideal line of automobile steering.Points which can not meet the ideal line are discussed carefully.To solve the vehicle steering center,three equivalent model and four wheel model are built respectively,we find the effect is the same when the side slip angle is small.(4)The higher the vehicle speed is,the lager the centrifugal force will be,and the same with the side slip angle.In order to verify the steering angle difference at high speedand low speed,EPS model which can simulate vehicle speed and engine speed and do the test are built.The difference of steering angle is indeed exist when the vehicle is at high speed and low speed,and the reason of the difference is caused by the residual angle of torsion bar.